1. Field of the Invention
The present invention relates to a new display unit, and particularly to an art for effectively performing cooling without damaging closed environment.
2. Description of the Related Art
For example, in the case of a liquid-crystal projector system for displaying an image by irradiating the light emitted from a light source onto a liquid-crystal light bulb and projecting the light passing through the liquid-crystal light bulb on a screen by a projection lens, various cooling methods have been used so far in order to prevent temperatures of the liquid-crystal light bulb and various optical components from rising due to the heat of the light source.
For example, there is a method of performing the cooling by supplying outside air into the housing of the liquid-crystal projector system by using a fan.
However, a method of cooling a housing by supplying outside air into the housing by a fan has a problem that not only the outside air but also dust are taken in at the same time and the dust attaches to a liquid-crystal light bulb and various optical component.
As a result, a problem occurs that the dust interrupts or diffuses the transmitted light of the liquid-crystal light bulb and thereby, stains or bleeding is produced on an image.
Therefore, in order to prevent the attachment of the dust, it is generally carried out that a dust-removing filter is attached to an outside-air intake.
However, even if the dust-removing filter is attached, it is impossible to remove dust smaller than the mesh of the filter. Therefore, a problem occurs that fine dust accumulates in the liquid-crystal projector system and dust attaches to the liquid-crystal light bulb and the various optical components in any case.
Moreover, in the case of this method, a problem occurs that the filter must be frequently cleaned although the filter is incomplete as dust-removing means.
Furthermore, when using a fan, the fan emits noises to the outside of the housing of the liquid-crystal projector system. Therefore, a problem occurs that unnecessary noises other than voices are produced while operating the liquid-crystal projector system and cause a user or audience to feel an uncomfortable sense.
Furthermore, a method of constituting an optical block including a liquid-crystal light bulb into a closed type in a liquid-crystal projector system and circulating air into the inside of the optical block is considered as a cooling method other than the above method.
To use the above method, however, there is a problem that it is necessary to improve the radiating performance of the closed optical block because the air capacity in the optical block is small and thereby, the structure of the liquid-crystal projector system becomes complex.
Therefore, it is an object of the present invention to prevent dust from entering a system and attaching to optical components as well as to be able to sufficiently cool the heat produced in the system.
To solve the above problems, a display unit of the present invention comprises a housing having a screen at its front and constituted by a closed structure, an optical block set in the closed housing, and connecting means for connecting the housing with the optical block to circulate air.
Therefore, the display unit of the present invention makes it possible to cool the optical block by circulating air between the housing and the optical block through the connecting means and cooling the air during its circulation. Moreover, because the optical block is located in the closed housing, any dust does not enter the optical block from the outside.
Furthermore, another display unit of the present invention comprises a housing having a screen at its front and constituted by a closed structure, an optical block set in the closed housing, first cooling means for cooling a light source, and second cooling means for cooling the optical block.
Therefore, because the another display unit of the present invention makes it possible to separately use the first cooling means and the second cooling means correspondingly to the light source and the optical block, it is possible to use proper cooling means correspondingly to the light source and the optical block greatly different from each other in calorific value. Therefore, it is possible to improve the cooling efficiencies of the light source and the optical block and moreover, more preferably constitute the display unit because degrees of freedom on the design of the light source and the optical block are increased.